ESS Bilbao, Bilbao, Spain
Bilbao, Faculty of Science and Technology, Bilbao, Spain
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
ESS-Bilbao, Zamudio, Spain
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
The Bilbao Accelerator RFQ is aimed to accelerate a 75 mA proton beam from 75 keV to 3 MeV, while keeping the beam both transversely and longitudinally focused, and presenting a minimum emittance growth. We report on the current status of the project, mainly focusing on the Beam Dynamics aspects of the design. Several particle simulations are carried out with RFQSIM, GPT and TRACK codes, in order to study the particle transmission of the RFQ under several circumstances, such as different current levels, vane geometry changes due to thermal stress, and different input beam characteristics obtained by changing the LEBT operation settings.
SLAC, Menlo Park, California, USA
We discuss the properties of the coherent electromagnetic fields of a very short, ultra-relativistic bunch in a rectangular vacuum chamber inside a bending magnet. The analysis is based on the results of a direct numerical solution of Maxwell’s equations together with Newton’s equations. We use a new dispersion-free time-domain algorithm which employs a more efficient use of finite element mesh techniques and hence produces self-consistent and stable solutions for very short bunches. We investigate the fine structure of the CSR fields including coherent edge radiation. This approach should be useful in the study of existing and future concepts of particle accelerators and ultrafast coherent light sources.
TUODN5
SLAC, Menlo Park, California, USA
The determination of wakefields for short bunches in accelerator structures with complex geometries and large spatial dimensions requires significant computational resources. The time domain code T3P developed at SLAC employs the higher-order finite element method for high fidelity modeling and parallel computation for large-scale simulation on state-of-the-art supercomputers. To facilitate wakefield calculation for short bunches, T3P has been enhanced through the implementation of a moving window technique which reduces computing resource requirements by orders of magnitude. For local refinement in the moving window, both a finer unstructured mesh and higher-order finite element basis functions can be employed. Applications demonstrating the efficacy of the technique include wakefield calculations of shallow tapers in storage rings, complex and long vacuum chamber transitions in energy recovery linacs (ERL) and higher-order-mode (HOM) couplers in superconducting rf cavities.
IHEP Beijing, Beijing, People's Republic of China
Tomsk State University, Tomsk, Russia
Institute of High Current Electronics, Tomsk, Russia
Royal Holloway, University of London, Surrey, United Kingdom
BNL, Upton, Long Island, New York, USA
Using the electromagnetic simulation code ECHO, we have found* a simple phenomenological formula that accurately describes the loss factor for short bunches traversing an axisymmetric tapered collimator. In this paper, we consider tapered collimators with elliptical cross-section and use the GdfidL code to calculate the loss factor dependence on the geometric parameters for short bunches. The results for both axisymmetric and elliptical collimators are discussed.
* A. Blednykh and S. Krinsky, Phys. Rev. ST-AB 13, 064401 (2010).
BNL, Upton, Long Island, New York, USA
The analysis of multi-layer beam tubes is a frequent problem and is usually solved with axially propagating waves. This treatment is ill suited to a short multi-layer structure such as the present example of a ferrite covered ceramic break in the beam tube at the ERL photo-cathode electron gun. This paper demonstrates that such structures can better be treated by radial wave propagation. The theoretical method is presented and numerical results are compared with measured network analyser data and Microwave Studio generated simulations. The results confirm the concept of radial transmission lines as a valid analytical method.
BNL, Upton, Long Island, New York, USA
BNL, Upton, Long Island, New York, USA
SLAC, Menlo Park, California, USA
CLASSE, Ithaca, New York, USA
LPI, Moscow, Russia
We calculate the coherent radiation in an undulator/wiggler with a vacuum chamber of arbitrary cross section. The backward radiation is a coherent and it has wavelengths about twice the period of the undulator/wiggler. Mostly of coherent radiation is going with the wavelengths approximately the bunch length at small angles however.
LLNL, Livermore, California, USA
NPS, Monterey, California, USA
The Naval Postgraduate School (NPS), Niowave, Inc., and Boeing have recently demonstrated operation of the first superconducting RF electron gun based on a quarter wave resonator structure. In preliminary tests, this gun has produced 10 ps-long bunches with charge in excess of 78 pC, and with beam energy up to 396 keV. Initial testing occurred at Niowave's Lansing, MI, facility, but the gun and its diagnostic beamline are planned for installation at NPS in the near future. The design of the diagnostic beamline is conducive to the addition of a Cerenkov radiator without interfering with other beamline operations. Design and simulations of a Cerenkov radiator, consisting of a dielectric lined waveguide will be presented. The dispersion relation for the structure is determined and the beam interaction is studied using numerical simulations. The characteristics of the microwave radiation produced in both the long and short bunch regimes will be examined.
ORNL, Oak Ridge, Tennessee, USA
ANL, Argonne, USA
Beam waveguide (BWG) geometry with two longitudinally uniform concave reflectors can support quasi-optical transverse resonances of electromagnetic waves and longitudinal power transmission. The quasi-optical resonance in BWG can be treated as a Gaussian beam. The BWG are often known to have high Q-factors while operating in higher order modes. The latest interests on these beam waveguides are the application for microwave or millimeter wave undulators for synchrotron radiation. The general properties of the BWG are discussed with the field solutions and dispersion properties derived with elliptical beam waveguides approximation. Potential applications of BWG for supporting circularly polarized wave are discussed.
SLAC, Menlo Park, California, USA
The vacuum chamber of the ILC Interaction Region (IR) is optimized for best detector performance. It has special shaping to minimize additional backgrounds due to the metal part of the chamber. Also, for the same reason this thin vacuum chamber does not have water cooling. Therefore, small amounts of power, which may be deposited in the chamber, can be enough to raise the chamber to a high temperature. One of the sources of “heating” power is the electromagnetic field of the beam. This field diffracts by non-regularities of the beam pipe and excites free-propagating fields, which are then absorbed by the pipe wall. In addition we have a heating power of the image currents due to finite conductivity of the metallic wall. We will discuss these effects as updating the previous results.
SLAC, Menlo Park, California, USA
Fermilab, Batavia, USA
UCLA, Los Angeles, California, USA
Injection of electron beams into laser driven picosecond scale accelerating structures demand highly synchronized electron beams with bunch lengths approaching the femtosecond scale. One-dimensional numerical studies of undulator interactions of 3.5 MeV sub-picosecond electron beams and THz pulse trains produced by optical rectification have shown substantial compression and a reduction in time of arrival jitter with respect to the accelerator drive laser from the scale of hundreds of fs to that of tens of fs. In this paper a THz undulator based compression and synchronization scheme is investigated.
UMiss, University, Mississippi, USA
Tech-X, Boulder, Colorado, USA